1. Field of the Invention
The present invention relates to with a surgical probe for laparoscopy and intracavitary tumour localization. A surgeon needs to localize a tumour in order to remove it and thus he usually makes use of the traditional diagnostic means to search for the tumour, such as: CAT, NMR, Scintigraphy. However during the operation, the surgeon can still need to better define the area to be cut and removed. Thus he can use a so-called "SURGICAL-PROBE": after injecting the patient with a radioisotope-doped drug capable of being absorbed by the tumour cells, the surgeon can detect the gamma radiations emitted by the radioisotope via a probe practically acting as a Geiger-Muller detector.
The probe sensitivity to gamma radiations is such that it gives analogic signals, whose number is proportional to the detected radioisotope concentration. The detected signals are then reversed into digital signals thus giving a luminous and/or noisy scale proportional to the detected radioisotope concentration.
By tracing the most active area, the tumour site can be localised.
2. Description of the Related Art
As an example the "MARTIN PROBE", presently on the market, is a cylindrical proportional tube, 30 mm in diameter, containing an ionisable gas and two electrodes to which a high voltage is applied: the gamma rays are detected by gas ionising and electrical signal generating means.
The availability of a small dimension probe with a good efficiency for low energy rays would be desirable.
The Martin Probe, however, has an excessive hindrance and a weak low energy-rays efficiency thus resulting in:
1) a very rough spatial resolution, such as 4 cm, which gives a bad tumour localisation
2) a bad tumour-to-background ratio resolution which makes the probe of scarce utility.
It is then clear that the poor obtainable advantages are limiting the use of the surgical probe.
Several probes are known on the market, all of them used in in intracavitary mode only, which is made of about 20 mm diameter cylindrical tube having inside a scintillating crystal positioned on the tip of the tube, coupled with a photomultiplier.
When the gamma radiations emitted by the radio pharmaceutical, previously injected into the patient, hit the scintillating crystal, a specific light is emitted and collected by the photomultiplier which, in turn, converts the optical into an electrical signal, which can then be used to vary a visible or voiced scale whose value is proportional to the radiation intensity. Furthermore, being the probe active area of a few square centimeters with the possibility of collimation, the spacial resolution results to be limited to a few centimeters.
The use of the described probe is only limited to the intracavitary mode or, in other words, when necessarily the surgeon opens the patient.
It is desirable however to use a probe via laparoscopy to detect with high precision the sites where radioactive tracers cumulate and indicate the presence of a tumour to be surgically removed, thus guiding the surgeon toward the exact tumour position with the possibility to discriminate tumoural from healthy tissue with a few millimeter precision.
Before the surgical operation it would be necessary to precisely locate the point of radioactive tracer maximum concentration together with the surrounding area affected by the surgical removable tumour.
U.S. Pat. No. 5,429,133 discloses a laparoscopic instrument having a hand-grippable base to which an elongate accessing tube is connected which extends to a tip. Extending inwardly from the tip is a detection support region within which a radiation transmissive window is formed. Immediately spaced from and behind the window a detecting crystal such as cadmium telluride is retained to detect the radiations emitted from a .sup.125 I source and retained in a mount structure designed to minimize noise generation due to microphonic (piezoelectric) phenomena.
PCT Application WO 94/03108, on which the preamble of present claim 1 is based discloses a laparoscopic surgical probe for localizing tumours and creating images of tumour affected radiation emitting organs comprising a first section based upon scintillator means for receiving radiation rays emitted from said radiation emitting organs and converting the radiation rays into light signals, light transmission means to transmit the light signals generated by said first section to a second section including a position sensitive light signal detector and electronic means for receiving said light signals and producing images of said radiation emitting organs.
U.S. Pat. Nos. 5,014,708 and 5,088,492 disclose multi-function devices wherein use is made of collimators in surgical probes.